MySQL query INSERT INTO Table with Examples ~ Tech Blog

Tuesday, 17 April 2018

MySQL query INSERT INTO Table with Examples

The main goal of database systems is to store data in the tables. The data is usually supplied by application programs that run on top of the database. Towards that end, SQL has the INSERT command that is used to store data into a table. The INSERT command creates a new row in the table to store data.

Basic syntax

Let's look at the basic syntax of the SQL INSERT command shown below.

INSERT INTO `table_name`(column_1,column_2,...) VALUES (value_1,value_2,...);

HERE

INSERT INTO `table_name` is the command that tells MySQL server to add new row into a table named `table_name`.
(column_1,column_2,...) specifies the columns to be updated in the new row
VALUES (value_1,value_2,...) specifies the values to be added into the new row

When supplying the data values to be inserted into the new table, the following should be considered while dealing with different data types.

String data types - all the string values should be enclosed in single quotes.
Numeric data types - all numeric values should be supplied directly without enclosing them in single or double quotes.
Date data types - enclose date values in single quotes in the format 'YYYY-MM-DD'.

Example:
Suppose that we have the following list of new library members that need to be added into the database.

Full names	Date of Birth	gender	Physical address	Postal address	Contact number	Email Address
Leonard Hofstadter		Male	Woodcrest		0845738767
Sheldon Cooper		Male	Woodcrest		0976736763
Rajesh Koothrappali		Male	Fairview		0938867763
Leslie Winkle	14/02/1984	Male			0987636553
Howard Wolowitz	24/08/1981	Male	South Park	P.O. Box 4563	0987786553	lwolowitz@email.me

Lets' INSERT data one by one. We will start with Leonard Hofstadter. We will treat the contact number as a numeric data type and not enclose the number in single quotes.

INSERT INTO `members` (`full_names`,`gender`,`physical_address`,`contact_number`) VALUES ('Leonard Hofstadter','Male','Woodcrest',0845738767);

Executing the above script drops the 0 from Leonard's contact number. This is because the value will be treated as a numeric value and the zero (0) at the beginning is dropped since it's not significant.
In order to avoid such problems, the value must be enclosed in single quotes as shown below -

INSERT INTO `members` (`full_names`,`gender`,`physical_address`,`contact_number`) VALUES ('Sheldon Cooper','Male','Woodcrest', '0976736763');

In the above case , zero(0) will not be dropped
Changing the order of the columns has no effect on the INSERT query as long as the correct values have been mapped to the correct columns.
The query shown below demonstrates the above point.

INSERT INTO `members` (`contact_number`,`gender`,`full_names`,`physical_address`)VALUES ('0938867763','Male','Rajesh Koothrappali','Woodcrest');

The above queries skipped the date of birth column, by default MySQL will insert NULL values in columns that are skipped in the INSERT query.
Let's now insert the record for Leslie which has the date of birth supplied. The date value should be enclosed in single quotes using the format 'YYYY-MM-DD'.

INSERT INTO `members` (`full_names`,`date_of_birth`,`gender`,`physical_address`,`contact_number`) VALUES ('Leslie Winkle','1984-02-14','Male','Woodcrest', '0987636553');

All of the above queries specified the columns and mapped them to values in the insert statement.If we are supplying values for ALL the columns in the table, then we can omit the columns from the insert query.
Example:-

INSERT INTO `members` VALUES (9,'Howard Wolowitz','Male','1981-08-24','SouthPark','P.O. Box 4563', '0987786553', 'lwolowitz[at]email.me');

Let's now use the SELECT statement to view all the rows in the members table.SELECT * FROM `members`;



 
membership_number full_names gender date_of_birth physical_address postal_address contct_number email
1 Janet Jones Female 21-07-1980 First Street Plot No 4 Private Bag 0759 253 542 janetjones@yagoo.cm
2 Janet Smith Jones Female 23-06-1980 Melrose 123 NULL NULL jj@fstreet.com
3 Robert Phil Male 12-07-1989 3rd Street 34 NULL 12345 rm@tstreet.com
4 Gloria Williams Female 14-02-1984 2nd Street 23 NULL NULL NULL
5 Leonard Hofstadter Male NULL Woodcrest NULL 845738767 NULL
6 Sheldon Cooper Male NULL Woodcrest NULL 976736763 NULL
7 Rajesh Koothrappali Male NULL Woodcrest NULL 938867763 NULL
8 Leslie Winkle Male 14-02-1984 Woodcrest NULL 987636553 NULL
9 Howard Wolowitz Male 24-08-1981 SouthPark P.O. Box 4563 987786553 lwolowitz@email.me

membership_number	full_names	gender	date_of_birth	physical_address	postal_address	contct_number	email
1	Janet Jones	Female	21-07-1980	First Street Plot No 4	Private Bag	0759 253 542	janetjones@yagoo.cm
2	Janet Smith Jones	Female	23-06-1980	Melrose 123	NULL	NULL	jj@fstreet.com
3	Robert Phil	Male	12-07-1989	3rd Street 34	NULL	12345	rm@tstreet.com
4	Gloria Williams	Female	14-02-1984	2nd Street 23	NULL	NULL	NULL
5	Leonard Hofstadter	Male	NULL	Woodcrest	NULL	845738767	NULL
6	Sheldon Cooper	Male	NULL	Woodcrest	NULL	976736763	NULL
7	Rajesh Koothrappali	Male	NULL	Woodcrest	NULL	938867763	NULL
8	Leslie Winkle	Male	14-02-1984	Woodcrest	NULL	987636553	NULL
9	Howard Wolowitz	Male	24-08-1981	SouthPark	P.O. Box 4563	987786553	lwolowitz@email.me

Notice the contact number for Leonard Hofstadter has dropped the zero (0) from the contact number. The other contact numbers have not dropped the zero (0) at the beginning.

Inserting into a Table from another Table

The INSERT command can also be used to insert data into a table from another table. The basic syntax is as shown below.

INSERT INTO table_1 SELECT * FROM table_2;

Let's now look at a practical example, we will create a dummy table for movie categories for demonstration purposes. We will call the new categories table categories_archive. The script shown below creates the table.

CREATE TABLE `categories_archive` (       `category_id` int(11) AUTO_INCREMENT,       `category_name` varchar(150) DEFAULT NULL,       `remarks` varchar(500) DEFAULT NULL,       PRIMARY KEY (`category_id`)     )

Execute the above script to create the table.
Let's now insert all the rows from the categories table into the categories archive table. The script shown below helps us to achieve that.

INSERT INTO `categories_archive` SELECT * FROM `categories`;

Executing the above script inserts all the rows from the categories table into the categories archive table. Note the table structures will have to be the same for the script to work. A more robust script is one that maps the column names in the insert table to the ones in the table containing the data.
The query shown below demonstrates its usage.

INSERT INTO `categories_archive`(category_id,category_name,remarks)  SELECT category_id,category_name,remarks FROM `categories`;

Executing the SELECT query

SELECT * FROM `categories_archive`

gives the following results shown below.




category_id category_name remarks
1 Comedy Movies with humour
2 Romantic Love stories
3 Epic Story acient movies
4 Horror NULL
5 Science Fiction NULL
6 Thriller NULL
7 Action NULL
8 Romantic Comedy NULL
9 Cartoons NULL
10 Cartoons NULL

category_id	category_name	remarks
1	Comedy	Movies with humour
2	Romantic	Love stories
3	Epic	Story acient movies
4	Horror	NULL
5	Science Fiction	NULL
6	Thriller	NULL
7	Action	NULL
8	Romantic Comedy	NULL
9	Cartoons	NULL
10	Cartoons	NULL

Summary

The INSERT command is used to add new data into a table
The date and string values should be enclosed in single quotes.
The numeric values do not need to be enclosed in quotes.
The INSERT command can also be used to insert data from one table into another.

Tech Blog

Tuesday, 17 April 2018